pull: Add support for http-headers option

Some deployments may want to gate access to content based on things
like OAuth.  In this model, the client system would normally compute a
token and pass it to the server via an API.

We could theoretically support this in the remote config too, but
that'd be a bit weird for OAuth as the information is dynamic.
Therefore this cleans up the code a little bit to more clearly handle
the case that the fetcher is initialized from both remote config
data plus pull options.

Closes: #574
Approved by: giuseppe

src/libostree/ostree-fetcher.c

@@ -53,6 +53,7 @@ typedef struct {
   GLnxLockFile tmpdir_lock;
   int base_tmpdir_dfd;
 
+  GVariant *extra_headers;
   int max_outstanding;
 
   /* Queue for libsoup, see bgo#708591 */
@@ -148,6 +149,8 @@ thread_closure_unref (ThreadClosure *thread_closure)
 
       g_clear_pointer (&thread_closure->main_context, g_main_context_unref);
 
+      g_clear_pointer (&thread_closure->extra_headers, (GDestroyNotify)g_variant_unref);
+
       if (thread_closure->tmpdir_dfd != -1)
         close (thread_closure->tmpdir_dfd);
 
@@ -336,6 +339,16 @@ session_thread_set_cookie_jar_cb (ThreadClosure *thread_closure,
                             SOUP_SESSION_FEATURE (jar));
 }
 
+static void
+session_thread_set_headers_cb (ThreadClosure *thread_closure,
+                               gpointer data)
+{
+  GVariant *headers = data;
+
+  g_clear_pointer (&thread_closure->extra_headers, (GDestroyNotify)g_variant_unref);
+  thread_closure->extra_headers = g_variant_ref (headers);
+}
+
 #ifdef HAVE_LIBSOUP_CLIENT_CERTS
 static void
 session_thread_set_tls_interaction_cb (ThreadClosure *thread_closure,
@@ -448,6 +461,17 @@ session_thread_request_uri (ThreadClosure *thread_closure,
       return;
     }
 
+  if (SOUP_IS_REQUEST_HTTP (pending->request) && thread_closure->extra_headers)
+    {
+      glnx_unref_object SoupMessage *msg = soup_request_http_get_message ((SoupRequestHTTP*) pending->request);
+      g_autoptr(GVariantIter) viter = g_variant_iter_new (thread_closure->extra_headers);
+      const char *key;
+      const char *value;
+
+      while (g_variant_iter_next (viter, "(&s&s)", &key, &value))
+        soup_message_headers_append (msg->request_headers, key, value);
+    }
+
   if (pending->is_stream)
     {
       soup_request_send_async (pending->request,
@@ -812,6 +836,16 @@ _ostree_fetcher_set_tls_database (OstreeFetcher *self,
     }
 }
 
+void
+_ostree_fetcher_set_extra_headers (OstreeFetcher *self,
+                                   GVariant      *extra_headers)
+{
+  session_thread_idle_add (self->thread_closure,
+                           session_thread_set_headers_cb,
+                           g_variant_ref (extra_headers),
+                           (GDestroyNotify) g_variant_unref);
+}
+
 static gboolean
 finish_stream (OstreeFetcherPendingURI *pending,
                GCancellable            *cancellable,